Railway traffic controlling apparatus



1396- 1935- Hv G. BLOSSER ET AL I RAILWAY TRAFFIC CONTROLLING APPARATUSFiled June 3, 1935' n J a WWW m mm n m w A Patented Dec. 24, 1935UNl'l'EQ T'i'h'd RAILWAY TRAFIFEC CONTROLLING APPARATUS Herman G.Blosser, Pittsburgh, and Charles W.

Failor, Forest Hills, Pa, assignors to The Union Switch & Signal(Jcmpany, Swissvale, Pa, a corporation cf Pennsylvania Application June3, 1933, Serial No. 674,200

14 Claims.

Our invention relates to railway traffic controlling apparatus, and morespecifically to apparatus for clearing out highway crossing cutsections, operating detector locking track circuits, as well as forclearing out detector track sections generally, in signaling systemsemploying coded track circuit current for the control of wayside and cabsignals.

One feature of our invention is the provision of apparatus of the abovecharacter which will not cause improper operation of cab or waysidesignals. Another feature is the provision of complete broken downinsulated rail joint protection, without requiring numerous controlrelays and using a minimum number of control line wires per trackcircuit.

We will describe one form of track circuit clearing apparatus embodyingour invention, and will then point out the novel features thereof inclaims.

The acco; panying drawing is a diagrammatic view of a stretch of railwaytrack with the associated apparatus embodying our invention as appliedto the clearing out of highway crossing cut sections upon the passage ofa train.

Referring to the drawing, the block section lL-G, in which trafiicnormally moves from left to right in the direction of the arrow, isdivided into out sections DE, E-F, and F-G for the purpose ofcontrolling highway crossing signals KS and KS at locations E and )3.Each of the above sections is provided with a track transformer T and acode-following track relay TR. Adjacent track circuits have staggeredinstantaneous polarities, and the track relays are of the two-elementtype having a local winding l and a CDntTOl winding 2 so that reversetorque, tending to open the front contacts of these relays, will bedeveloped should. a breakdown of the. insulated rail joints occur.

For simplicity, the continuously operating code filters CT and GT atlocations D and G, ectlvely, are shown as supplying track circurrent ofbut two code frequencies, namely, current of 180 interruptions pernunute over the odically closed contact It'll], and current of w.nterruptions per minute over the periodically closed Contact for thecontrol of wayside and cab signals. In practice, additional codefrequencies, selected in accordance with traffic conditic-ns in advance,will normally be used to pro- ,ontrol for multiple aspect wayside andcab a. One form of code transmitter, and one anangement of apparatus forselecting the code to be applied to a track section in accordance withtrafiic conditions in advance, are shown and described in Letters Patentof the United States No. 1,773,472, granted to P. N. Bossart on August19, 1930, and so these parts of the system are illustrateddiagrammatically in the present case 5 to simplify the disclosure.

When current of 180 code frequency flows in the rails of section DEwhich is assumed to be unoccupied, relay TR will operate in step withthe code impulses, and the periodic closing of contacts 3- 3 and 3--5 ofthis relay will cause direct current to be supplied alternately to oneand then to the other half of the primary winding of decodingtransformer DT, to induce an alternating voltage in the secondaryWinding.

he circuit of the secondary Winding of transformer T is tuned to the I83code frequency by reactor X and condenser C so that the slow releasingdecoding relay DR, which is energized from the tuned circuit through arectifier R will remain picked up as long as section D-E is suppliedwith rail current of 180 code frequency. In a similar manner, theuntuned decoding relay DB which is energized through rectifier R willremain picked up as long as section D--E is supplied with rail currentof either 180 or 80 code frequency. If the code frequency is 180, frontcontacts 6-l and 3fl-3l of relays DR and DB will be closed, therebycausing lamp G of signal S to become energized. Signal S will thereforeindicate proceed. When the code requency is 80, relay DR, will bereleased, and relay DR will be energized, so that lamp Y of signal Swill be lighted over contacts 6-8 and 30-3l of relays DR and DB Uponshunting of relay TR by a train, or prolonged interruption of the railcurrent, relay DR will release due to the collapse of the secondaryvoltage in transformer DT, so that back contact 3G32 will close thecircuit for lamp R. of signal S, to provide a stop indication forfollowing trafiic.

Assuming again that section D-E is unoccupied and that relay TR isfollowing 180 code, contact 53-46 of relay IE will close periodically,maintaining slow releasing relay K energized, and contact 9ll will alsoclose periodically to maintain the slow releasing relay L energized overfront contact l2 of relay K Relay L controls the energization ofcrossing signals X8 and as long as relay L is energized, these signalswill remain inoperative by virtue of the open back contact H3. Therelays K and L can be conveniently termed decoding relays because, aswill appear from the description which follows, 55

these relays respond to code operation of the track relay TR We shallnow explain the operation of the apparatus during the passage of a trainfrom location D, through the various cut sections.

When the train enters section D-E, the operation of relay TR will cease,opening contact 9-l0 .to release relay K which in turn will releaserelay L thus initiating operation of the crossing signals X5 at locationE. When the train enters section E-F, relay TR, will release, releasingin turn relays K3 and L which are controlled in the same manner asrelays K and L associated with section D-E. The release of relay K willcause relay XR to release, due to the opening of front contact 14,thereby starting the'operation of the crossing signals X5 over 'backcontact 16 of relay XR. The release of relay L closing back contact I1,will result in energization of the auxiliary code transmitter ACT whichis provided for the purpose of supplied to transformer T plying aclearing or detectioncode to track section DE to clear out this sectionfollowing the passage of the train into section E-F. This detection codemust be of such character as not to cause response of the wayside signalS or of cab signals on a following locomotive which may have overrunlocation D, and, at the same time, this code must cause operation ofrelay TR in such manner that both relays K and L will be- I come pickedup to stop the operation of the crossing signals X8 One type ofdetection code which will accomplish the above results consists of arelatively short on period, followed by a relatively long ofi period,these periods being repeated successively. This type of code is employedin the apparatus which we have illustrated, and is supover theperiodically operated contact l8 of transmitter ACT wire l9, and backcontact 28 of relay L The trans mitter illustrated diagrammatically atACT may comprise, for example, a motor element which, when energized,causes rotation of the contactoperating cam to produce the short on andlong off intervals of the code. Relay TR will pick up during each oninterval of the detection code, thus causing pick up of relay K which issuinciently slow releasing to bridge the oif code intervals, duringwhich relay L will receive energy over contact 9-H of relay TR andcontact I2 'of relay K Relay L is sufficiently slow releasing to bridgethe on code intervals, during which contact 9-H remains open. It will beapparent, therefore, that the detection code will beeifective to stopthe operation of crossing signals KS when no train is occupying sectionD'E. At the safe time, if the periodic frequency of the detection codeis sufficiently far removed from the code frequency of the traingoverning code used for controlling cab and wayside signals,

relays. If desired, a detection or if a suitable time ratio isestablished between the duration of the on and off detectioncodeperiods, there will be no response of wayside or locomotive decodingrelays such as DR or DB 'That is, the selection of a detection codefrequency appreciably far removed from the train governing codefrequency, or the suitable choice of the on and 01f time ratio willprevent the energization of decoding relays if the on period is ofinsufiicient duration for pick up of these code comprising a relativelylong on period, followed by a relatively short off period can also beused, provided the time elements of relays K L and DR are suitablyadjusted, or code frequency tuning of all wayside and locomotivedecoding relays is used. Obviously, the detection code may be of anysuitable character, provided it does not pick up relays DR or DR andprovided further that it operates relay TR in such manner as to pick uprelays K and L When the train enters section F-G, relays TR- K and Lwill all become deenergized, and the auxiliary code transmitter ACT willbecome energized over back contact 25 of relay L and will furnish adetection code to section E-F, same manner that the detection code wasfurnished to section D E, as previously described,

to energize relay XR'over front contacts l4 and I5 of relays K and Lthereby stopping the operation of signals X3 The picking up of relays Kand L train from section EF will cause transmitter ACT to becomeinoperative due to opening of relay L .It should be noted.

signal S to indicate stop by virtue of the closing of back contacts 21and 33. As soon as the train clears section FG, train governing currentof code frequency, suitably selected by code selection apparatus whichis not shown in the drawing, will be supplied by transmitter CT totransformer T thereby causing operation of relay TR which results in theenergization of relays K and L The opening of back contact 2! of relay Lwill stop the operation of transmitter ACT and track section E-F willthen be supplied with current of 80 code frequency over the periodicallyoperated contact 29 of relay TR. and front contact 28 of relay L RelayTR? will follow the 80 code and will relay this code to track sectionD-E and 26 of relays TR and L in the same martner that it previouslyrelayed the detection code supplied by transmitter ACT As soon as theblock in advance of section F-G is cleared by the train, train governingcurrent of '180 code Since section F-G is the last section in the blockDG, no special detection code such as that furnished by transmitters ACTand ACT is required in this section because any of the standard traingoverning codes furnished by transmitter GT can be used to clear relaysK and L The on and off periods of the train overcontacts 25 5 thereby 3the individual sections with in the which follows the exit of thegoverning codes being of substantially equal duration, relays K and Lthe same release time, which is true of relay groups K L and notnecessarily K L in which can have approximately groups the relays K andK should preferably have a substantially longer releasing time thanrelays L and L to insure satisfactory operation on a detection codehaving a short on and a long oil period. If a detection code comprisinga long on and a short off period is used, relays L and L will have alonger release interval than relays K and K but when the latter code isused, the increased release time of relays L and L may cause a sli htdelay in the starting of the crossing signals KS and KS To summarize, wehave provided a track circuit clearing or train detecting system whichrequires a number of control line wires, does not interfere with theoperation of wayside or cab signals, and permits relaying oi the traingoverning and detection codes to several rear sections without requiringadditional line wires and apparatus for purpose.

It will be apparent that our system can also be adapted for operation oncoded direct current track circuits, by substituting direct cu:- rentcode-following track relays for the relays TR, and by eliminating thetrack transformers T and substituting a direct current source for thealernating current source BX-CX.

Should foreign current be present, or a mechanical defect develop ineither of the codefollowing relays TR or TR resulting in a failure offront contact 8-18 to open, theassociated relay L or L will becomedeenergized, removing train governing code from the rear track circuitsup to the wayside signal location D, and causing signal S to indicatestop. Similarly, should back contact 9-ll fail to both relays of group KL or K U, will become-deenergized, and the stop indication will again bedisplayed by signal S.

It will be noted that the circuit for the crossing signal control relayXR. includes a front contact of each of relays L and K Although the useof front contact 55 of relay L would alone be sufiicient to check thatrelay TR is following code, the inclusion of front contact it of relay Kmakes possible a quicker response of relay for starting operation of thecrossing signal, since relay K is arranged to release before relay LAlthough we have herein shown and described only one form of apparatusembodying our invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of our invention.

Having thus we claim is:

1. In combination, a first and a second section of railway trackeachnorroally supplied with a train governing code comprising railcurrent periodically varied at a frequency selected in accordance withtraffic conditions in advance of said sections, means efiective whensaid second section becomes occupied for discontinuing the supply ofsaid train governing code to said first section and for supplying therails of said first section with a detection code comprisingperiodically varied current having consecutive periodic variations ofunequal duration, a codefollowing track relay for said first sectioncapable of following either oi said two codes, a siow acting relaycontrolled by said track relay in such manner as to become energizedwhen the track relay is following either of said two codes and to becomedeenergized when the described our invention, what track relay isshunted, an indicator controlled by said slow acting relay forindicating the occupancy of said first section, and a signal forgoverning trafiic entering said first section con trolled by said trackrelay and responsive to operation of the track relay on said traingoverning code but not said detection code.

2. In combination, a first and a second section of railway track eachnormally supplied wit-h a train governing code comprising rail cur rentperiodically varied at a frequency selected in accordance with trafiicconditions in advance of said sections, means effective when said secondsection becomes occupied for discontinuing the supply of said traingoverning code to said first section and for supplying the rails of saidfirst section with a detection code comprising periodically variedcurrent having consecutive periodic variations of unequal duration, acodefollowing track relay for said first section capable of followingeither of said two codes, a slow acting relay controlled by said trackrelay in such manner as to become energized when the track relay isfollowing either of said two codes and to become deenergized when thetrack relay is shunted, an indicator controlled by said slow actingrelay for indicating the oc-- cupancy of said first section, a. signalfor governing traffic entering said first section controlled by saidtrack relay and responsive to operation of the track relay on said traingoverning code but not said detection code, and means effective whenboth said sections become unoccupied for discontinuing the supply ofsaid detection code and restoring the supply of said train governingcode.

3. In combination, a first and a second section of railway track, meansfor supplying to the rails of said second section a train governing codecomprising current periodically varied at a frequency selected inaccordance with traflic conditions in advance, a first code-followingtrack relay for said second section capable of following said traingoverning code, a first control relay which becomes energized when saidfirst track relay is following said train governing code and whichbecomes deenergized when said first track relay is shunted, a source ofdetection code comprising periodically varied current having consecutiveperiodic variations of unequal duration, means including a back contactof said control relay for rendering said source eifective for supplyingsaid detection code to the rails of said first section, a secondcode-follow ing track relay for said first section capable of followingeither of said two codes, a second control relay which is energized whensaid second track relay is following either of said two codes and whichbecomes deenergized when said second track relay is shunted, a signalcontrolled by said second control relay for indicating the occupancy ofsaid first section, and means including a front contactof said firstcontrol relay effective when said first track relay is following saidtrain governing code for relaying the train governing code from saidsecond section to the rails of said first section.

i. In combination, a section of railway track normally supplied with atrain governing code comprising rail current periodically varied at afrequency selected in accordance with traffic conditions in advance ofthe section, means for at times discontinuing the supply of said traingoverning code and for supplying the rails of said section with adetection code comprising periodically varied current having consecutiveperiodic variations of unequal duration, a codefollowing track relayfor'said section capable of following either of said two codes, and atrain indicator for said section controlled by said track relay in suchmanner as toprovide one indication when said track relay is followingeither of said two codes and to provide another indication when saidtrack relay is shunted.

5. In combination, a section of railway track normally supplied with atrain governing code comprising rail current periodically varied at afrequency selected in accordance with traffic conditions in advance ofthe section, means for at times discontinuing the supply of said traingoverning code and for supplying the rails of said section with adetection code comprising periodically varied current having consecutiveperiodic variations of unequal duration, a codefollowing track relay forsaid section capable of following either of said two codes, a slowacting relay controlled by said track relay and capable of bridging theoperation thereof when the track relay is following either of said twocodes, and a train indicator for said section controlled by said slowacting relay. 6. In combination, a section of railway track normallysupplied with a train governing code comprising rail currentperiodically varied at a frequency selected in accordance with trafficconditions in advance of the section, means for at times discontinuingthe supply of said train governing code and for supplying the rails ofsaid section with a detection code comprising periodically variedcurrent having consecutive periodic variations of unequal duration, acodefollowing track relay. for said section capable of following eitherof said two codes, a first slow acting relaycontrolled by said trackrelay and capable of bridging the operation of the track relay onalternate periodic variations of said two codes, and a second slowacting relay controlled by said track relay and said first slow actingrelay and capable of bridging the operation of the track relay onalternate periodic variations of said two codes occurring between saidfirst mentioned alternate periodic variations, and a train indicator forsaid section controlled by said second. slow acting relay.

7.'In combination, a first and a second section of railway track, afirst coding device for supplying said second section with a traingoverning code comprising rail current periodically varied at a givenfrequency, a first code-following track relay for said second section, asecond coding device effective'for supplying a detection code to saidfirstsection when said first track relay is shunted, said detection codecomprising periodically varied rail current having consecutive periodicvariations of unequal duration, means including a code-following contact'of said first track relay for relaying said train governing code to therailsof said first section when said 7 second section is unoccupied, asecond codefollowing track relay for said first section capable offollowing either of said two codes, and a train indicator for said firstsection controlled by said second track relay in such manner as toassume a first condition when the second track relay isfollowing eitherof said two codes and to assume a second condition when the second trackrelay is shunted. V

8. In combination; a stretch of railway track divided into an approachand a clearing section, means for supplying said clearing section with atrain governing code comprising coded alternating current havingsubstantially equal on and off periods, a first code-following trackrelay for said clearing section, means effective when said first trackrelay is following code for supplying said train governing code to therails of said approach section, means eifective when said first 7substantially equal on and off periods, means for at times discontinuingthe supply of said train governing code and for supplying the rails ofsaid section with a detection code comprising coded alternating currenthaving on and oil" periods of unequal duration, train governingapparatus responsive to said train governing code but unresponsive tosaid detection code, a code-following track relay for said section, anda train indicator controlled by said track relay in such manner as toprovide one indication when said track relay is following said traingoverning or said track clearing code and to provide another indicationwhen said track relay is shunted.

10. In combination, a stretch of railway track intersected by a highwayand comprising a signal approach section and a signal clearing section,a crossing signal for the intersection, means effective when saidclearing section is unoccupied for supplying both said sections with atrain governing code comprising coded alternating rail current havingsubstantially equal on and off periods, coding means responsive to theentry of a train into saidclearing section for supplying said approachsection with a detection code comprising coded alternating rail currenthaving on and off periods of unequal duration, train governing apparatusresponsive to, said train governing code but unresponsive to saiddetection code, means responsive to the entry of a train into saidapproach section for causing operation of said crossing signal, andmeans associated with said approach section and responsive to said traingoverning code and said detection code for clearing said crossing signalwhen the train clears said approach section.

11. In a coded wayside and cab signaling system for highway crossings onrailroads in which a train governing code comprising coded alternatingcurrent having substantially equal on and off periods is normallysupplied to the rails for governing wayside and cab signals, thecombination with a signal at the crossing, of means for actuating saidsignal effective when a train enters the section approaching saidsignal, and means effective when the train clears the approach sectionfor supplying a detection code to the rails of the approach section forclearing said signal, said detection code comprising coded alternatingcurrent having unequal on and off periods the relative time values ofwhich are adjusted in such manner as to prevent response of the waysideand cab signals on said detection code.

comprising coded alternating current having 12. In combination, twoadjoining sections of railway track, means for supplying coded railcurrent to one of said sections, a code-following track relay for saidone section, a decoding relay responsive to code operation of said trackrelay, and means including a contact of said track relay and a contactof said decoding relay for supplying rail current to the other of saidtwo sections.

13. In combination, two adjoining sections of railway track, a source ofcoded current and a code-following track relay connected with the railsof one of said sections, a decoding relay responsive to code operationof said track relay, a slow acting relay controlled by said decodingrelay, and means including a contact of said track relay and a contactof said slow acting relay for supplying rail current to the other ofsaid two sections.

14. In combination, two adjoining sections of railway track, means forsupplying one of said sections with rail current of a first or of asecond code in accordance with trafiic conditions, a code-followingtrack relay for said one section, a decoding relay which becomesenergized in response to operation of said track relay on either saidfirst or said second code, means including a back contact of saiddecoding relay for supplying rail current of said first code to theother of said two sections, and means including a contact of said trackrelay for supplying rail current of said second code to said othersection.

HERMAN G. BLOSSER. CHARLES W. FAILOR.

